1. Field of the Invention
The present invention relates, in general, to an ultra-miniaturized electron optical microcolumn and, more particularly, to a ultra-miniaturized electron optical microcolumn which is able to be manufactured into a compact size and optimize the trajectory of an electron beam.
2. Description of the Related Art
Generally, although manufacturing apparatuses and inspection apparatuses using an electron beam, which are used in semiconductor and display industries, have very high resolution compared to existing optical equipment, the size of an electron column for generating and controlling an electron beam is bulky. Thus, the electron column using an electron beam has a large acceleration voltage ranging from a few kV to tens of kV, as well as a large size, possibly causing defects to samples or structures of a substrate. Further, the electron column has a low processing speed and thus low productivity, so that the electron column is limited to use as a manufacturing device for a mask for a semiconductor, an inspection device for a thin film transistor (TFT) substrate for a display, or the like.
To solve this problem, developed has been a miniaturized electron optical microcolumn, which is generally called a ‘micro-column or microcolumn’. The microcolumn can be miniaturized into a compact size of a few˜tens mm in length, so that a plurality of miniaturized electron optical microcolumns can be arranged in a single unit, thereby maximizing the operation performance of the unit. Further, since the acceleration voltage of an electron beam can be set to 1 kV or less, minimizing the possibility of damage to structures of a substrate or a sample can be ensured.
However, such a miniaturized electron column has problems that it has reduced resolution compared to the bulky electron column, due to its simple structure and low acceleration voltage, and that, in a case where a probe current to a target surface decreases, it is difficult to detect secondary electrons generated from the target surface when the target surface is scanned at high speed with an electron beam in order to increase resolution. Therefore, further research is required to solve these problems. Further, in a case where a plurality of miniaturized electron columns are arranged in order to improve the operation performance of an assembly of the electron columns, it is difficult to precisely align the electron columns together, thereby requiring further research to develop a structure for the integration of a multiplicity of electron optical columns in a single silicon substrate.
Korean Patent laid-open Publication No. 10-2003-0073598 discloses a conventional microminiaturized electron column, which includes a source lens which is composed of an extraction grid (extractor or extraction electrode) for extracting electrons, an anode grid (accelerator or acceleration electrode) for accelerating electrons, and a limit grid (limiter or limiting electrode) for limiting the size of a electron beam, octupole electrostatic double deflectors for deflecting electron beams, and a focusing lens which is composed of an einzel lens for focusing electron beams.
Like this, the conventional microminiaturized electron optical column is configured such that it is composed of the source lens and the focusing lens with the octupole electrostatic double deflectors interposed therebetween, so that it is very difficult to precisely align centers of these lenses during assembly. Further, although an error of alignment between the source lens and the focusing lens can be corrected to some extent using the arrangement of the octupole electrostatic double deflectors, in this case, the structure of the assembly becomes complicated as does the application method of drive voltage.